Csound is described as 'sound design, music synthesd signal processing system, providing facilities for composition and performance over a wide range of platforms' and is an app in the Audio & Music category. There are more than 10 alternatives to Csound for a variety of platforms, including Mac, Windows, Linux, Online / Web-based and Self-Hosted solutions. The best alternative is Pure Data, which is both free and Open Source. Other great apps like Csound are SuperCollider (Free, Open Source), Max/MSP (Paid), Sonic Pi (Free, Open Source) and PraxisLIVE (Free, Open Source).
Pd (aka Pure Data) is a real-time graphical programming environment for audio, video, and graphical processing. It is the third major branch of the family of patcher programming languages known as Max (Max/FTS, ISPW Max, Max/MSP, jMax, etc.
A real time audio synthesis engine, and an object-oriented programming language specialised for music. SuperCollider was created in 1996 by James McCartney, Since version 3 it is released as free software.
Interactive visual programming environment for music, audio, and media In use for over twenty years by performers, composers, artists, scientists, teachers, and students, Max is the way to make your computer do things that reflect your individual ideas and dreams.
Soinc Pi is a live-coding audio software. Learn to code creatively by composing, improvising or performing in an incredible range of styles from classical through to algorave. FEATURES Simple enough for computing and music lessons.
Orca is an Esoteric Programming Language and live-coding environment for musical experimentation. In Orca, each letter of the alphabet is an operation, lowercase letters operate on bang, uppercase letters operate each frame.
Pyo is a Python module to help DSP script creation. Pyo contains classes for audio signal processing. With pyo, the user will be able to chain such classes directly in Python, and to manipulate them in real time through the interpreter.
Faust (Functional Audio Stream) is a functional programming language for sound synthesis and audio processing with a strong focus on the design of synthesizers, musical instruments, audio effects, etc.
Nyquist is a language and IDE for sound synthesis and music composition. It is implemented in C and C++ and runs on Win32, OSX, and Linux. Nyquist combines a powerful functional programming style with efficient signal-processing primitives.